Pest description and crop damage The adult is a small, shiny black wasp. Larvae feed within a single seed and eventually destroy it.
To help reduce chalcids after fall harvest, cultivate at least 1 inch deep with a springtooth harrow, to bury infested seed. Follow with irrigation. "Setting back" the hay by cutting or clipping the stand in May reduces populations. Destroy or burn any chaff stacks and screenings by April 1. Remove volunteer and waste-area alfalfa plants.
Insecticides do not provide effective control for this pest.